India Reports Rare Case of Vaccine-Derived Polio Virus Transmission from Child to Dad
In a rare and alarming occurrence, Kerala, India, has reported a case of vaccine-derived polio virus (VDPV) transmission from a child to his healthy father. This discovery has raised concerns about the potential spread of the polio virus within the community.
The investigation was conducted by the World Health Organisation, the ICMR-National Institute of Immunohematology, and the Mumbai-based ICMR-National Institute of Virology. The findings were published in the journal Vaccines and were the result of a two-stage research conducted in 2022.
The research focused on examining the excretion of poliovirus and non-polio enteroviruses in 157 children with inborn errors of immunity (IEI) from different regions of India. During the study, it was discovered that one child from Kerala’s Malappuram district was excreting the virus after receiving two doses of the oral polio vaccination (OPV).
Upon discovering this data, it was immediately reported to the WHO, the health ministry, and ICMR Delhi on August 1, 2022, which prompted an epidemiological inquiry in the neighborhood.
During the investigation, it was found that the father of the child, a healthy 32-year-old man who showed no symptoms, was also excreting the same virus. Interestingly, all other community samples came back negative.
This research highlights the danger of immunodeficiency-related vaccine-derived polioviruses (iVDPVs) for the resurgence of polio. While it does not provide details about the father’s recovery, it emphasizes the need for a long-term monitoring strategy for iVDPV to ensure continuous efforts in the post-polio eradication stage. The research suggests that enhancing IEI surveillance will enable prompt detection and monitoring of iVDPV excretion to reduce the risk of transmission.
Instances of iVDPV transmission to healthy contacts are rare worldwide. A study conducted in the US found that 23 children, one of whom had a severe combined immunological deficit, were affected by VDPV transmission in an unvaccinated neighborhood. Another investigation in Spain also documented the spread of iVDPV to uninfected contacts. The report from Kerala is one of the few cases of iVDPV transmission within a family.
India, along with ten other countries in the WHO Southeast Asia Region, was declared polio-free in 2014. Since January 2011, there have been no newly reported cases of polio from naturally circulating poliovirus in India.
However, vaccine-derived polioviruses have occasionally been detected. These viruses are derived from a strain of the oral polio vaccination (OPV). The OPV, a live weakened polio virus, replicates in the gut and boosts immunity by generating antibodies. According to the World Health Organisation, in unvaccinated populations, especially in areas with poor sanitation, hygiene, or overcrowding, the OPV strain may undergo rare genetic changes and spread.
The UN health organization warns that “the longer vaccine-derived polio virus survives and the more genetic changes it undergoes, the lower the population’s immunity.” In rare cases, the virus produced by the vaccination can transform into a form similar to the wild polio virus, leading to paralysis.
This rare case of vaccine-derived polio virus transmission from a child to his father in Kerala serves as a reminder of the ongoing challenges in eradicating polio completely. It emphasizes the importance of continued surveillance and monitoring to prevent the resurgence of this debilitating disease.